bruce Posted June 5, 2017 Share Posted June 5, 2017 Perhaps a slightly bizarre question, but I’d value your thoughts.... I’m currently carrying out a repair on the bass end of an accordion which has had a midi retrofit. It was done years ago, and is pretty “old skool” technology - mechanical switches fabricated from silver plated springs hitting against busbars. I vaguely remember seeing these springs in old Maplin catalogues, in the “build your own organ keyboard” days.... Anyway - these days it’s generally done using hall effect switches and little magnets on the pushrods. The electronics is straightforward, I just need to work out how to mount the things. In particular, how to fix the magnets to the pushrods. The rods are metal, about 1mm diameter. They move sideways by about 1cm when the button is pressed. The magnets are tiny neodymium discs, about 3mm in diameter, 1mm thick. The magnets need to be mounted on the side of the pushrod. Generally this is done with an adhesive, although some installers have little custom-made clips. My question - what sort of glue would be best? Epoxy? Superglue? Hot-melt? Something tells me I should be using epoxy, but the long setting time means that it may be awkward to hold the tiny component in place while it’s setting. Superglue/cyanoacrylate is certainly quick setting, but it sometimes seems quite brittle when set? And I’ve never really had success using hot melt for intricate work - too stringy! Any thoughts ? Also thinking of wrapping it with a small length of heat shrink once the glue has set.... Link to comment Share on other sites More sharing options...
alistermorton Posted June 5, 2017 Share Posted June 5, 2017 Gorilla glue? Yes, it takes longer to set than superglue but it's strong. Failing that, hot melt might well work, but it can go brittle too. Link to comment Share on other sites More sharing options...
Dave m Posted June 5, 2017 Share Posted June 5, 2017 Superglue to hold, epoxy to fix in place? Link to comment Share on other sites More sharing options...
pjb304 Posted June 5, 2017 Share Posted June 5, 2017 You can get superglue with rubber in it which is designed to be more flexible, an example is Loctite 410 so should be less brittle than normal cyanoacrylate. Link to comment Share on other sites More sharing options...
bruce Posted June 5, 2017 Author Share Posted June 5, 2017 Superglue to hold, epoxy to fix in place?Now there’s an interesting question. Wikipedia, that well known font of knowledge, suggests that epoxies bond by 3 methods - mechanically, by proximity, and ionically - with the ionic variant being by far the strongest, where the adhesive reacts and bonds with the surface. But if you have a lower layer of superglue to tack it in place, you’ll not get physical contact between the workpiece and the epoxy ? Link to comment Share on other sites More sharing options...
Andrew C Posted June 5, 2017 Share Posted June 5, 2017 Araldite do 3 grades of setting speed, though I believe there is a trade off with ultimate strength. The fastest sets in 90secs or so. Link to comment Share on other sites More sharing options...
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